docs: def perform_service_validate(
          self,
          ticket=None,
          service_url=None,
          headers=None,
          ):
          '''
          Fetch a response from the remote CAS `serviceValidate` endpoint.
          '''
          url = self._get_service_validate_url(ticket, service_url=service_url)
          logging.debug('[CAS] ServiceValidate URL: {}'.format(url))
          return self._perform_cas_call(url, ticket=ticket, headers=headers)